Question

我需要使用一些oracle内置方法（解析，strlength，...）将字符串转换为数字我不知道如何为方法内的变量赋值，我不知道在哪里放置声明部分。

CREATE OR REPLACE FUNCTION EXAMPLE (param IN VARCHAR2) 
RETURN NUMBER AS
BEGIN

  SELECT <string_handling_using_param> 
    INTO var 
    FROM DUAL;

  RETURN TO_NUMBER(<some computation using var>);

END EXAMPLE ;

我已尝试过围绕此函数的一些变体，比如添加一个OUT参数来存储中间变量，但是我无法从常规SQL中调用该函数...

有关如何实现这一目标的任何建议吗？

Answer 1

如果我理解正确，你只需要定义“var”变量......

create or replace FUNCTION EXAMPLE (param IN VARCHAR2)
RETURN NUMBER
AS
   var VARCHAR2(100);  -- This datatype may need modification
BEGIN
  select <string_handling>
  into   var
  from   dual;

  return to_number(<some computation using var>);
END EXAMPLE ;

根据您正在做的事情，可能有一个更好的方法，不需要SELECT ... FROM DUAL：

create or replace FUNCTION EXAMPLE (param IN VARCHAR2)
RETURN NUMBER
AS
   var VARCHAR2(100);  -- This datatype may need modification
BEGIN
  var := <string_handling>;

  return to_number(<some computation using var>);
END EXAMPLE ;

Answer 2

create or replace FUNCTION EXAMPLE (param IN VARCHAR2) 
RETURN NUMBER AS 
    -- declare section between AS and BEGIN
    var varchar2(100);
BEGIN   
   select <string_handling> into var from dual;  
   -- also note that many built-in functions can be done directly
   -- without calling a select, so in many cases
   -- var := substr(param,1,10) <or some other string handling>;
   -- is perfectly acceptable too. 
   return to_number(<some computation using var>); 
EXCEPTION -- if you need an exception handler
   when value_error then
      <do something with it or set a default return value or whatever>
END EXAMPLE ;

Oracle Pl / SQl：具有中间结果的自定义函数

2 个答案: